Answer
x = 28
y = 32
Explanation:
Non-vertical angles (top and bottom) are congruent
Thus
5x - 15 = 4x + 13
x = 28
and so each non-vertical is
5(28) -15 = 125
4(28) + 13 = 125
Diagonals bisect vertex angles (left and right) Thus we have one vertical angle as (y + y) = 2y
and another vertical angle as (y -9) + (y - 9) = 2y - 18
All the angles in a kite adds up to 360
So
125 + 125 + 2y + (2y - 18) = 360
250 + 4y - 18 = 360
4y = 128
y = 32